The present invention relates generally to valves for controlling fluid flow that operate to permit and disrupt fluid flow automatically, and more particularly to ring-type valve structures used as air inlet valves and exhaust valves in high pressure gas compressors and fluid pumps. Specifically, the present invention relates to an improvement in the ring valve structures described in co-pending United States Letters patent application Ser. No. 07/278,225, filed Nov. 30, 1988 by inventors Jerre F. Lauterbach, Nathan Ritchie and Richard F. Miller entitled "RING VALVE TYPE AIR COMPRESSOR", and owned by the assignee of the present application, now issued as U.S. Pat. No. 5,022,832.
Ring type valves per se are well known in the art, and have a wide acceptance in use for air compressors and pumps Basically, these ring type valves are opened and closed by pressure differential on opposite sides of the ring valve. It is also heretofore known to include biasing of spring devices along with such ring valves in order to accurately control valve movement upon a pressure differential which is above the spring force of the spring selected in each case. In this way, the valve is opened or closed only upon reaching a pre-determined pressure differential dependent on the spring properties of the spring chosen and the mass of the valve, wherein the valve action can be predicted. The said U.S. Letters patent application No. 07/728,225 (issued Jun. 11, 1991 as U.S. Pat. No. 5,022,832 was directed to solving certain problems in the prior art as exemplified by constructions such as those shown in Herzmark, U.S. Pat. No. 2,382,716 issued Aug. 14, 1945; Peters, U.S. Pat. No. 1,225,321 issued Apr. 10, 1917; and Garland, U.S. Pat. No. 3,786,834 issued Jan. 22, 1974. Such constructions generally disclose use of spring washers that are freely supported to bias the ring valves in a desired position. This type of spring washer and ring valve assembly requires additional supporting structure to retain the spring washer, which decreases the efficiency of the air compressor by lowering the compression volume of each cylinder at the end of the suction stroke, and increases the cost, weight, and complexity of the valve assembly. The said co-pending U.S. Letters patent application Ser. No. 07/278,225 (Pat. No. 5,022,832) solved those problems of the prior references by providing a biasing means for the ring valve having a peripheral region which is connected to the fluid pump to retain the ring valve between the cylinder head and the bias means, and thus eliminate the additional supporting structure and the decreased efficiency of the prior devices.
However, it has been found that in certain applications, because of air turbulence and the like, some problems have arisen in such improved device, such as the ring valves taking on a "spinning" action, and becoming worn due to resonance conditions causing the ring valve to impact the valve seat with excessive force and becoming dented about the regions of contact between the valve seat and the ring valve, and thus, eventually, causing a leaky condition. Thus, additional improvements and invention are needed to solve those problems.
One approach followed in the patent to Cooper, U.S. Pat. No. 2,728,351, issued Dec. 27, 1955, was to machine the cylinder block and liner with a tapered surface and to position the ring valve such that its deflection into a conical or frustoconical form is limited by the tapered surface. One drawback with this approach is the cost and risk of a machining error which could cause the entire cylinder block and/or liner to become scrap. Another drawback is the size-limited nature of the ring valve. As the cylinder bore size changes the ring valve must change so that its size matches the size of the tapered surface which changes as the bore size changes.
In one embodiment of the present invention the first drawback is overcome by the use of a separate retainer. The retainer provides the tapered surface to be used as a back up for the ring valve deflection, but is a lower cost piece that does not require special machining of the cylinder block and liner. If a machining error is made in the retainer, a lower cost part is scrap and the cylinder block and liner are not affected. In the present invention the same retainer can be used with differently sized bores, such as a 35/8" bore as well as a 37/8" bore. Thus greater versatility is provided by the present invention.